Violence has flared again in Ethiopia's Oromia region, a day after dozens of people were killed in a stampede when police tried to disrupt an anti-government protest during a religious festival.

The state broadcaster raised the death toll to 55 from the earlier official count of 52 following the incident, while three other people remain in hospital with serious injuries.

After the stampede, clashes between security forces and protesters erupted on Sunday evening and continued into Monday morning in the towns of Bishoftu and Ambo.

Relatives of those killed in Sunday's stampede are flocking to Bishoftu, 27 miles south-east of the capital, Addis Ababa, increasing tensions.

The annual Irrecha thanksgiving festival had drawn huge crowds, and the stampede occurred as people ran to escape police firing tear gas and rubber bullets and shooting live rounds into the air after anti-government protesters approached the stage where religious leaders were speaking.

At least 52 people were crushed to death. A witness said some of those killed were still being recovered from ditches where they fell while trying to flee.

There also were reports of arrests.

"Some people tried to come out en masse this morning to protest the deaths of holiday-goers on Sunday and also demand the release of people arrested during the celebrations," one witness, Nimona Negash said.

"Today's protesters were peaceful but dispersed by police violently. I'm not aware of any deaths this morning, but it was violent. But I'm aware of live bullets used this morning in other vicinities of this town."

He said he saw seven bodies pulled from a deep ditch until he could no longer stand to watch.

The Oromia region has been experiencing deadly anti-government protests since November 2015 as people call for wider political freedom and the release of detained opposition figures and journalists.

Ethiopia's government, a close security ally of the west, has been accused of quashing dissent and blocking internet access. The US recently spoke out against what it called the excessive use of force against protesters, calling the country's situation "extremely serious".

Ethiopia's government has accusing the protesters over the tragedy. President Mulatu Teshome Wirtu, on a state visit to Italy, blamed the stampede on "the action of some hooligans".

The head of the Oromia region's spokesman's office, Fikadu Tessema, said some groups were trying to "continue the violence that they orchestrated on Sunday".

He said they were trying to portray the stampede as caused by live bullets fired by government forces.

"I can assure you 100% that all the 52 victims died of a stampede, and didn't have bullet wounds on their bodies," he insisted.

"The current situation in Oromia is not out of control. We are taking measures to bring back our peace."